The nervous system relies on precise wiring to accurately and consistently process information. This precision relies on accurate long distance navigation by axons and dendrites, as well as recognition of these neurites by each other to form appropriate synapses. In particular, axons of a similar function share a similar path and may selectively fasciculate as they travel that path. Upon reaching their targets, the axons defasciculate to appropriately form synapses with their specific target. Selective axon fasciculation and synapse formation both rely on intercellular adhesion. One family of adhesion molecules that could mediate both types of adhesion is the cadherin family. Cadherins are cell-cell adhesion molecules expressed along extending neurites and at developing and stable synapses. I propose to test the hypothesis that cadherins are mediating developmental events in the olfactory system, specifically in axon extension and synapse formation. I will begin my study by examining where and when cadherins are expressed in the olfactory system in vivo, to determine what potential roles they could be playing based upon their location of expression. To test specific hypotheses regarding the functions of cadherins, I will develop a series of in vitro assays. These assays will allow perturbation of cadherin and catenin function in a more easily manipulable system. I will thus examine the olfactory system, both in vivo and in vitro, to determine the role that molecular cues may be playing in guiding axonal and synaptic specificity.